In recent years, efforts are being made to realize commercialization of a substrate comprising a ceramic tile and a conductor layer of copper or copper alloy directly joined to the ceramic tile. Since this substrate has nothing to intervene between the conductor layer and the ceramic tile, it permits quick diffusion of the heat generated by a semiconductor element deposited on the conductor layer, encouraging efforts to develop a semiconductor of increased capacity to be used on the substrate.
The substrate of the type described above, however, poses the following problem and has room for further improvement. Specifically, this substrate has the possibility of entailing the phenomenon that, while the semiconductor element is operating, the ceramic tile sustains cracks near the terminal connected to the conductor layer.